Dark; blue, not found in Scripture, but frequently referred to in the Old Testament under the name of Sihor, i.e., "the black stream" (Isa. 23:3; Jer. 2:18) or simply "the river" (Gen. 41:1; Ex. 1:22, etc.) and the "flood of Egypt" (Amos 8:8). It consists of two rivers, the White Nile, which takes its rise in the Victoria Nyanza, and the Blue Nile, which rises in the Abyssinian Mountains. These unite at the town of Khartoum, whence it pursues its course for 1,800 miles, and falls into the Mediterranean through its two branches, into which it is divided a few miles north of Cairo, the Rosetta and the Damietta branch. (See Egypt.)
Easton's Bible Dictionary. M.G. Easton. 1897.